Method of forming bellows tubing



Jan. 19, 1932. w. B. CLIFFORD I 1,842,149

METHOD OF FORMING BELLOWS TUBING Filed Sept. 19, 1928 2 Sheets-$heet 1 .wambg wmx Jan. 19, 1932. w. B. CLIFFORD 1,842,149

METHOD OF FORMING BELLOWS TUBING Filed Sept. 19, 1928 2 Sheets-Sheet 2 50/ v I 8 i Patented Jan. 19 1932 PATENT oFFIcE WALTER B. CLIFFORD, F CAMBRIDGE, MASSAGHFSETTS nnrnon or FORMING nnntows rimme- Application filed September 19, 1928. Serial No. ?,038.

The present invention relates to a method of forming bellows tubing and more particularly to such a method adapted to be employed in conjunction with the forming ma- 5, chine disclosed in my Patent No. 1,689,620, .grantedOCtoberZdO, 1928. The present in-- vention is a continuation in part of that disclosed and claimed in my earlier application Serial No. 221,570, filed September 23, 1927, According to the present. invention, the tube is first sealed at opposite ends with an opening or passage provided in one end for the introduction of fluid pressure during the forming operation. The end fitting provided with the fluid pressure passage projects slightly beyond the outer diameter of the tube to provide a shoulder for engagement during the. forming operation. lin certain cases the tube may be provided with a fitting upon both ends and in other cases the-tube may be left in its initial cupped form and sealed with'a fitting only at the open end. in either case, however, this method of pro: cedure has decided advantages due in part to the fact that the joint formed between the fitting and the tube end is automatically tested by the high pressures employed during the forming operation, and in part to the fact that the operation of sealing the end of the tube is much simplified by applying the fitting to the plain tube before formation of the bellows folds rather than thereafter.

In the drawings illustrating the various steps carrying out the present invention,

Fig. 1 represents a thin wall cupped tube; i Fig. 2, a tube with the closed end removed; Fig. 3, the same tube with the ends flanged outwardly for the reception of a fitting;

Fig. i, the same tube with the fitting introduced and the outturned end spun inwardly over the fitting; in each of the preceding views the tube is broken midway of its ends to economize in space; and the thi'clmess of the tube is exaggerated;

Fig. 5 illustrates the fitting hermetically sealed to the tube end with a soldered joint; Fig. 6, the completed assembly after the formation of the bellows folds;-

Fig. 7 represents a similar cupped tube to that shown in Fig, 1, but of somewhat different dimensions;

Fig. 8, the same tube with the cupped end shaped to receive a valve;

Fig. 9, the valve locked in cupped end; Fig. 10, the outward spinning and assembly with an end fitting; in each of the preceding Figures 7 to 10 inclusive, the tube is broken away intermediate its ends, and for at purposes of illustration the thickness is shown somewhat exaggerated;

Fig. ll, he complete tube assembly prior to forming; and

Fig. 12, the completed bellows assembly at with the thickness of the bellows wall exaggerated for purpose of illustration.

Referring to the illustrated embodiment of the invention, acupped tube is indicated at 20. This tube may be drawn in the usual re manner to the desired dimensions and with a grained size and temper properly suited for the work which it must undergo in the tormetion of the bellows folds. After the completion of the cupped drawn tube which may '15 approximate one inch in diameter with a length oi ten inches and a wall thickness of seven-thousandths of an inch, the closed end is removed as indicated in Fig. 2, and thereafter the opposite ends of the tube are spun an outwardly at 22 and 23 to form an annular -oiiset portion, as indicated in Fig. 3. ll'iis spinning may be accomplished through the a e within the a 7 employment of a spinning roll indicated at 24, which is moved transversely of the axis of the tube during a relative rotation of the tube and roll. The annular enlargement upon opposite ends of the tube is designed for the reception of an end fitting 26 which is somewhat larger in diameter than the external diameter of the tube but is received within the annular enlargement, seating against the shoulder formed thereon. This end fitting, as indicated in Fig. 4, may comprise a ribbed disk 28 having a hollow stud 30 riveted centrally therein, as indicated. The fittin at the opposite end may be provided wit a larger stud 32. After assembly of the head or disk within the'outer enlarged end of the tube, the latter is spun inwardly at 34 and 10 the head is thereafter sealed by solder 36 which serves not only to seal the annular joint between the edge of the disk and the tube end, but also the joint between the disk and stud 30, the annular rib- 38 formed intermediate the disk serving to promote the flow of solder toward the two joints. After completion of the tube assembly, as shown in Fig. 5, the stud 32 being closed to hermetically seal one end of the tube, the assembly is mounted within a forming machine of the type disclosed in the patent referred to, with the end forming plates 40 located behind the shoulder 42, and the tube contracted into a series of bellows folds to produce the bellows indicated at i l in Fig. 6.

In the method as outlined in Figs. 7 to 12 inclusive, a tube is first shaped at the closed end to form the stepped indentation 52. 00- operating with this stepped indentation is a valve member 54 having a more or less resilient locking portion 56 projecting from the bottom which is adapted to be forced into .the lowest portion 58 of the indentation 52 and upon pressure being applied, spread outwardly, as shown in Fig. 9, to lock the portion 56 rigidly within the lowermost recess 58. Thereafter the joint may be sealed with solder as indicated at 60. Subsequent to the application of the valve to the closed end of the tube, the open end is spun outwardly at 62 for the reception of a head 64- which is indicated as provided with a threaded stud 66 and a projecting ring 68 adapted for the reception of a tube 70 which acts as a stop to limit the movement of the bellows in collapsed position. As shown more particularly in Fig. 11, the stop tube is assembled with the head 64. and is located in assembled position by spinning or flanging the ring 68 outwardly at 72. Thereafter the head and stop assembly is inserted in the portion 62 of the tube which is then turned inwardly at 7 4 and soldered at 76 to hermetically seal the tube except for the provision of the fluid passage 78. Thereafter the completed bellows assembly 80 is formed in the machine as previously described.

It will be evident that in this alternative mode of procedure only one end of the tube is left open for closure with an end fitting. Obviously, if no fitting was desired at 'the closed end of the tube, it would be essential only to apply a single end fitting to the open end, thus eliminating the necessity of one end fitting and the joint created thereby.

With this method, the end fitting in each case is applied prior to the formation of the bellows, and during such formation the relatively high fluid pressure employed serves as a means for automatically testing not only the tube structure itself, but the strength and tightness of the joint between the end of the tube and the fitting. Inasmuch as the pressures ordinarily employed are on the order of 500 ounds per square inch and upwards, it

will e evident that an improperly ointed end fitting will cause failure of pressure and failure of the forming operation, as well as a weak or porous tube structure.

Not only does such a method permit testing of the end joint during the formation of the bellows and simplify the application of the end fitting due to its application to the plain tube, but in addition, this method permits the employment of an end fitting having a diameter on the order of the initial tube rather than the outer diameter of the finished bellows. This is important not only because it reduces the length of the circumferential joint, but also because a smaller and lighter fitting may be employed. In many uses for devices of this character, especially where eX- treme sensitivity is required, the weight of the bellows structure is governed to a substantial extent by the character and size of the end fitting. In usual practice, where the end fittings are applied after the formation of the bellows folds, it has not been the usual custom to employ end fittings substantially smaller than the diameter of the outer convolution, the fittings as a rule being mounted upon and secured to the last convolution in a manner which will be obvious to those skilled in the art.

What is claimed is:

1 The method of making bellows tubing which consists in forming a thin-wall tubular shell working the wall of the shell outwardly at an open end to form an enlarged annular portion, assembling an end fitting with a passage formedtherein within the enlarged annular portion, sealing the end fitting to the tubular shell, and forming a series of bellows folds in the shell through the employment of internal fluid pressure introduced through the passage in theend fitting.

2. The method of making bellows tubing which consists in forming a thin-wall tubular shell, working the wall of the shell outwardly at an open end to form an enlarged annular portion, assembling an end fitting with a passage formed therein within the enlarged annular portion, turning the peripheral edge of the annular portion inwardly over the corresponding edge of the end fitting, hermetically sealing the fitting to the tubular shell, and forming a series of bellows folds substantially larger at the outer convolutions than the diameter of the end fitting through the employment of fluid pressure introduced internally through the passage in the end fitting.

3. The method of making bellows tubing which consists in forming a thin-wall tubular shell, working the wall of the shell outwardly at an open end to form an enlarged annular portion, assembling an end fitting with a passage formed therein within the enlarged annular portion, sealing the end fitting to the enlarged annular portion, and introducing fluid pressure internally'through the passage in the end fitting while maintaining the end fitting in sealing engagement with a pressure source by rigidly supporting the shoulder formed by the enlarged annular portion.

4. The method of making bellows tubing which consist in forming a recessed portion in the closed end of a thin-wall tubular shell, assembling a fitting having an expansible locking portion in the previously formed recess in the closed end, and expanding the locking portion of the fitting to lock the latter firmly within the recessed portion of the shell. 7

5. The method of making bellows tubing which consists in forming a recessed portion in the closed end of a thin-wall tubular shell, assembling a fitting having an expansible looking portion in the previously formed recess in the closed end, expanding the locking portion of the fitting to lock the latter firmly within the recessed portion of the shell, closing the opposite open end of the shell with a fitting having a fluid passage extending therethrough, and forming bellows folds through the employment of' internal fluid pressure introduced through the passage in the end fitting.

6. The method of producing bellows folds with an interior stop, which consists in assembling and connecting a head and an in-.

terior stop, next mounting and connecting the assembled head and stop in a thin-wall tube, and finally forming bellows folds in the tube by fluid pressure introduced therein through one end of the tube.

7. The method of making bellows tubing which comprises forming a peripheral shoulder adjacent an open end of a thin-wall tube for receiving and locatin an end fitting, assembling an end fitting fiaving a head seated against the shoulder and a fluid passage extending therethrough, sealing the end fitting to the 'tube, and introducing fluid pressure into the tube through the passage in the end fitting while maintaining the fitting in sealing engagement with a pressure source by a support engaged behind the shouldered portion of the tube.

8. The method of making bellows tubing which comprises forming a peripheral shoulder adjacent an open end of a tube for receiving and locating an end fitting, the tube being provided with an annular portion betube being provided with an annular portion beyond the shoulder, assembling an end fitting having a head with the head received within the annular portion and seated against the shoulder, spinning the annular portion over the head when in assembled position, and sealing the fitting to the wall of the tube.

' WALTER B. CLIFFORD.

' yond the shoulder, assembling an end fitting having a head with the head received within the annular portion and seated against the shoulder, and sealing the fitting to the tube wall.

9. The method of making bellows tubing which compgises forming a peripheral shoulder ad acent an open end of a tube for receiving and locating an end fitting, the 

